As apparatus for reproducing a multi-channel audio signal, a real multi-speaker system where a plurality of (for example six) speakers are installed has been in practical use.
In recent years, apparatus has been proposed to reproduce multi-channel audio by outputting an audio signal as beams by using a single array speaker (for example, refer to JP-T-2003-510924). The apparatus described in JP-T-2003-510924 inputs the same audio signal into the speaker units at the same time or with slightly shifted timings to output the audio signal in a beam shape based on the principle of superposition. That is, as shown in FIG. 2, by inputting an audio signal into speaker units with timings slightly shifted from each other, audio beams are formed in oblique direction. By appropriately setting the timing shift (delay time), it is possible to control the directivity in a desired direction to form audio beans.